The mode of action of carbonic anhydrase inhibitors (CAI) involves their intracellular interaction with the enzyme. By regulating the cellular drug concentration, the processes by which CAI enter and exit cells can influence the drug-enzyme interaction. The here described research will study both, the cellular transport processes for CAI, and their effect on carbonic anhydrase. In order to investigate these phenomena in patients, human blood cells (erythrocytes and leukocytes) will be used as cellular models. However, in order to evaluate the pertinence of using blood cells as indicators of processes occuring in the eye, cellular material from the rat will also be investigated. Leukocytes are included in this study as morphologically typical mammalian cells, as opposed to the specialized cellular architecture of erythrocytes. The overall research involves the following phases: (1) characterization of transport mechanisms for CAI in human erythrocytes and leukocytes; (2) development of a procedure for the quantitative determination of CAI in plasma and tissues; (3) kinetic evaluation of the interaction of CAI with carbonic anhydrase in human blood cells, and correlation of these processes with levels of CAI in plasma and blood cells of normal volunteers and of glaucoma patients; (4) characterization of cellular transport and of interaction with carbonic anhydrase of CAI in blood cells.